The present invention relates to an image forming apparatus for forming an image on a recording medium.
When image data is to be outputted in an image forming apparatus such as a laser printer and copying machine, a toner image is developed on a photoconductor drum based on the image data, and is transferred on a recording medium such as paper. Then heat and pressure are applied by a fixing device, and an image is formed on the recording medium. Since heating by the fixing device requires a predetermined time, several means have been devised in the conventional apparatus to reduce time from turning on of power to enabling of image formation. Referring to FIGS. 12 and 13, the configuration of reducing the time from turning on of power to enabling of image formation in a copying machine 200 will be described, using an example of the configuration for reducing the time from turning on of power to enabling of image formation. FIG. 12 shows the control configuration in a copying machine 300. FIG. 13 shows the conventional processing of starting image formation applied in the copying machine 300.
As shown in FIG. 12, the copying machine 300 includes: an AC (alternating current) power supply 11; a main power supply switch 12 for turning on and off the AC power supply 11; a DC power supply 13 for converting the AC power supply power inputted from the AC power supply 11 and producing the DC (direct current) power supply output as the first and second DC power supply output; an AC drive section 14 for driving the fix-heating section 21 by heating power; a sub-power supply switch 15 as a power supply switch on the operation panel or the like; a power supply control section 16B for controlling the second DC power supply output from the DC power supply 13; an overall controlling section 17C for controlling creation of an image page; an engine controlling section 18 for controlling the fixing system and sheet feed system (not illustrated); a main relay 19 for switching the supply of power to the AC drive section 14; a fixing roller 20 for applying heat and pressure to the recording medium with a toner image transferred thereto by a photoconductor drum (not illustrated); a fix-heating section 21 consisting of an induction heating coil for heating the fixing roller 20; a motor 22, for rotating the fixing roller 20, consisting of a motor for rotating the fixing roller 20; and a temperature sensor 23 for detecting the temperature of the fixing roller 20.
FIG. 12 does not include the illustration of a sheet feeding means of the copying machine 300, image forming means including a photoconductor drum, means for communication with an external device such as a PC, or image reading means for reading a document. The fixing device contains a fixing roller 20, fix-heating section 21, temperature sensor 23 and motor 22.
Then the operation of the copying machine 300 will be described with reference to FIG. 13. As shown in FIG. 13, when the main power supply switch 12 is turned on, the AC supply power is converted by the power supply 13 and is outputted to the power supply control section 16B as the first DC power supply output (Step S71). Then the power supply control section 16B is activated by the first DC power supply output (Step S72). Then evaluation is made to see whether or not the sub-power supply switch 15 is turned on by the operator (Step S73).
If the sub-power supply switch 15 is not turned on (NO in Step S73), the system goes to Step S73. If the sub-power supply switch 15 is turned on (YES in Step S73), the start signal is outputted from the sub-power supply switch 15 and is inputted into the power supply control section 16B. When the start signal has been inputted, a power supply control signal is generated and outputted by the power supply control section 16B, and is inputted into the DC power supply 13. When the power supply control signal has been inputted, the second DC power supply output is generated and outputted by the second DC power supply 13 and is inputted into the overall controlling section 17 and engine controlling section 18 (Step S74).
When the second DC power supply has been inputted, the overall controlling section 17C starts to operate (Step S75A). In parallel with the Steps S75A, the engine controlling section 18 also starts operation when the second DC power supply has been inputted (Step S75B). When at least one of the Steps S75A and S75B has started, initial communication is tried between the overall controlling section 17C and engine controlling section 18 (Step S76). Evaluation is made to see whether or not communication has been established between the overall controlling section 17C and engine controlling section 18 (Step S77). In order for communication to be established between the overall controlling section 17C and engine controlling section 18, both the overall controlling section 17C and engine controlling section 18 must have been started.
If initial communication is not established (NO in Step S77), the system proceeds to Step S76. If initial communication has been established (YES in Step S77), the main relay 19 is turned on and the AC supply power outputted from the AC power supply 11 is inputted into the AC drive section 14, and the control signal is generated and outputted from the engine controlling section 18 to be inputted into the AC drive section 14 and motor 22. When the AC supply power and control signal have been inputted, the AC heating power is outputted from the AC drive section 14 and is inputted into the fix-heating section 21. Then the fixing roller 20 is heated and warm-up operation is performed (Step S78).
After initial communication has been established, the overall controlling section 17C generates the power control command, which is inputted into the power supply control section 16B. Based on the power supply control command, power supply control signal is generated and outputted by the power supply control section 16B, and is inputted into the DC power supply 13. This is followed by correction of the preliminary rotation of the fixing roller 20 by the motor 22 with control signal inputted therein, and preliminary operations such as preliminary control of each section by the overall controlling section 17C and engine controlling section 18 (Step S79). Then this will terminate processing of image formation according to the conventional image-forming startup procedure.
The time from turning on of power to enabling of image formation can be reduced more by simultaneous activations of both the overall controlling section 17C in the Step S75A and the engine controlling section 18 in the Step S75B, than by the sequential activation of them.
It is also possible to arrange such a configuration that the power save mode is activated before the overall controlling section and engine controlling section are started. To put it more specifically, a power save mode operates as follows: After the main power supply switch is turned on, the power supply control means of the main relay for applying power to the fixing device is started first. The main relay is turned on by the started power supply control means, and the fixing device is heated to a predetermined temperature, whereby low power is supplied to the fixing device. Then the overall controlling section and engine controlling section are automatically started to perform initial communication. The engine controlling section having been started causes various forms of processing, such as heating of the fixing device and correction of preliminary rotation. Since the fixing device is heated before the overall controlling section and engine controlling section are started, the time from turning on of power to enabling of image formation can be reduced.
Similarly to the configuration of the aforementioned power save mode, after power has been turned on, the power save mode is activated. When the power save mode release command has been inputted, the overall controlling section and the engine controlling section are started. Such a configuration can also be considered (e.g. Patent Document 2).
[Patent Document 1] Official Gazette of Japanese Patent Tokkai-2000-214734
[Patent Document 2] Official Gazette of Japanese Patent Tokkai-2001-22234
An image forming apparatus incorporates a system CPU for managing the overall status of the image forming apparatus, and an engine CPU for controlling the sheet feed system and fixing device. After power has been turned on, the system CPU and engine CPU are started. Then the fixing control of the fixing device is provided by the engine CPU, according to the conventional method. Since a predetermined time is required to heat the fixing device, means have been devised in the conventional apparatus to reduce time from turning on of power to enabling of image formation.
The fixing heater of the fixing device is provided with a first fixing heater having a capacity for normal image formation, and a second fixing heater having a capacity greater than that of the first fixing heater. Before the image forming apparatus has been started, power is supplied to the second fixing heater to cause a sudden temperature rise. Then power is supplied to the second fix-heater after the image forming apparatus has been started, so that an image can be formed. In this manner, the time for enabling mage formation is reduced, according to the conventional method (e.g. Patent Document 3).
[Patent Document 3] Official Gazette of Japanese Patent Tokkai 2000-330430
In recent years, however, there has been a trend toward increasing size and multifunctionality of the image forming apparatus. The program read out by the overall controlling section is getting more and more complicated, and hence a long time is required to load such a program. More time must be spent to start the overall controlling section. In the configuration of the copying machine 300 shown in FIGS. 10 and 11, there is apprehension that the time required to start up the overall controlling section 17C in Step S75A of processing the image formation in the conventional image-forming apparatus may be longer than the time for starting up the engine controlling section 18 in Step S75B. To put it another way, even when the engine controlling section 18 has been started and the system is ready to heat the fixing device, it is necessary to wait for the overall controlling section 17C to be started up, according to the conventional apparatus.
In the configuration described in Patent Documents 1 and 2, the fixing device is heated at a low power in advance. This arrangement reduces the time for the fixing device to be heated to the temperature required for image formation. However, the starting of the overall controlling section and heating and preliminary heating of the fixing device are sequential, and this may cause a delay in starting the preliminary operation such as heating of the fixing device by the engine controlling section and correction of the preliminary rotation, subsequent to the completion of starting of the overall controlling section and the engine controlling section and completion of initial communication, similarly to the case of the configuration of the copying machine 300.
In recent years, an electromagnetic induction heater (IH) that does not take much heating time has come to be employed as a fix-heating section of the fixing device, in place of a halogen heater requiring a longer heating time to reach a predetermined temperature. As a result, the required time from turning on of power to enabling of image formation is affected more by the percentage of the increase in the startup time of the overall controlling section, than by the time of heating the fixing device.
Further, in recent years, there has been a trend toward increasing size and multifunctionality of the image forming apparatus. The program read out by the overall controlling section is getting more and more complicated, and hence a long time is required to load such a program. More time must be spent to start the overall controlling section. Thus, when the fixing control of the fixing device is provided by the engine controlling section after starting up of the system control section, the startup time of the system control section is very long. There is apprehension that this will increase the time from turning on of power to enabling of image formation, according to the conventional image-forming method.
According to the conventional arrangement of heating a second fixing heater having a greater capacity to reach the temperature that permits image formation, it is possible to reduce the time for reaching the temperature that permits image formation. However, this method fails to reduce the influence of the system control section startup time, upon the time from turning on of power to enabling of image formation.